Abstract

The foliar morphospecies Linopteris obliqua (Bunbury) Zeiller, 1899 was originally based on isolated pinnules from Middle Pennsylvanian (upper Westphalian) strata in the Sydney Coalfield in Nova Scotia, Canada. However, new finds from the type area, including segments of a cauline axis and some fronds, attached juvenile croziers, an attached ovule, and associated pre-pollen organ, allow for a more complete understanding of the whole Linopteris obliqua plant. It was arborescent, 9 m to 10 m tall, with fronds ca 7 m long. Ovules of the Hexagonocarpus-type were attached directly to the petiole near the base of the frond, and pre-pollen was produced by Potoniea-type structures. The plant produced seeds and pollen at different times to avoid self-pollination. Ovule production was periodic and accompanied by mass pinnule abscission. The venation, especially the areolate-vein geometry, is relatively invariable within the plant species, and thus provides the typus (blueprint) for distinguishing other linopterid species, especially when combined with two-dimensional probability surfaces, and traditional pinnule morphology. However, the venation must be viewed on the abaxial surface of the pinnules if it is to be reliably interpreted. The mode of vein reticulation is shown to be quite distinct from the anastomosis-pattern seen in the other medullosalean taxa, and is another character that separates the Potonieaceae from the rest of the order.

Wnuk, C. & Pfefferkorn, H.H. 1984. The life habits and palaeoecology of Middle Pennsylvanian medullosan pteridosperms based on in situ assemblage from the Bernice Basin (Sullivan County, Pennsylvania, U.S.A.). Review of Palaeobotany and Palynology 41, 329–351.View article